There are many different technologies currently used to build physical three-dimensional models using additive manufacturing technology, e.g. building a model layer by layer. Typically, a virtual design of the three-dimensional model, e.g. represented through computer-aided design (CAD) software or the like, is transformed into a plurality of thin (quasi-two-dimensional) cross-sectional layers which are built on one another in succession.
There are a number of known ways in which the cross-sectional layers may be formed. For example, it is known to sinter a selected sub-region of a deposited area of green material, e.g. by guiding a laser beam over the sub-region. Such an arrangement is disclosed in WO 2004/056512. Another example involves the use of a two-dimensional heat or light source arranged to melt or cure all of a selected sub-region at the same time by masking out the areas not to be melted. Such an arrangement is disclosed in US 2002/0149137.
Other techniques may involve extruding or otherwise depositing green material already in the correct shape of the cross-sectional layer (e.g. by reference to an x-y-z-table constructed from the virtual design data). The deposited material may then harden naturally or be cured (e.g. by a powerful light source) to form the desired cross-sectional layer.
In a yet further example, each desired cross-sectional layer may be cut out of a sheet material, wherein the model is built by gluing together the cut-out layers.
US 2005/208168 discloses a technique in which a desired cross section is formed on the surface of a heated drum and subsequently transferred from the drum onto and fused together with previously deposited layers.
US 2004/0224173 discloses a Solid Freeform Fabrication tool in which a three-dimensional model is built from heating successive films formed of a mixture of thermoplastic particles and a water-soluble polymer matrix using a thermal head.